1. Field of the Invention
This invention relates to a pattern generating apparatus utilizing the information processing technique for processing two-dimensional patterns, and more particularly to a pattern generating apparatus such as printer for generating patterns necessary or suitable for generating design data patterns used when pattern defects of reticle patterns and electron beam pattern drawing are inspected in a defect inspection apparatus for reticle patterns used for manufacturing semiconductor integrated circuits and LCDs.
2. Description of the Related Art
As the integration density of the semiconductor integrated circuit is increased, the number of basic figures constructing the pattern of the semiconductor integrated circuit is increased, and as a result, time for drawing the pattern and time for generating patterns used for inspection of the pattern are increased.
The conventional reticle pattern defect inspection apparatus is constructed by elements shown in FIG. 10, for example. A pattern F formed on a photomask 60 is enlarged, the enlarged pattern is divided into strips of a preset width and then the divided portions are continuously scanned. Light passing through the illuminated photomask is made incident on a photodiode array 70 via an enlarging optical system and a pattern is optically formed on the array. The thus formed image is subjected to the photoelectric conversion and then subjected to the A/D conversion by a sensor circuit 80. Measured pattern data output from the sensor circuit 80 is supplied to a comparator 90 together with photomask position data on an XY.theta. coordinate table output from a positioning circuit. Pattern design data used at the time of formation of the pattern for the photomask 1 is input from a magnetic disk (DK) for storing the data to a bit pattern generator 100 which generates bit (pattern) data and converts the pattern design data to a preset pattern and supplies the pattern to the comparator. The comparator subjects the input bit pattern data to a preset filtering process, compares the thus obtained pattern data with actually measured pattern data and determines that there is a pattern defect when the compared pattern data items do not coincide with each other.
The bit pattern generator 100 is substantially the same as a figure pattern generating apparatus for converting the input image to a bit pattern and generating the bit pattern. The more detailed construction of the conventional pattern generating apparatus corresponding to the above described bit pattern generator 100 is shown in FIG. 11 and the flow of data generated is shown in FIG. 12.
Cell data 112 representing parameters concerning the figure pattern constructed by the basic figures in a compressed form in a microprogramming manner is stored in a third memory 106 of a control section 107. The cell data is transferred from the third memory 106 to a cell data memory 101 which is a first memory at high speed in the unit of cell. After this, the cell data 112 is transferred from the cell data memory 101 to a figure analyzer 102 to convert the cell data 112 represented in a compressed form into coordinate values (i.e. basic figure data 113) for each basic figure.
A figure unfolder 103 receives the basic figure data 113 for each figure, sequentially generates basic figure patterns 114 represented by the basic figure data 113, and transfers the same to a pattern memory 104 which is a second memory. The basic figure pattern 114 generated in the unit of cell is read out from the pattern memory 104 by raster scanning by means of a readout section 105.
In the conventional figure pattern generating apparatus with the above construction, time required for generating the pattern of one cell is generally longer than time for transferring the cell data because of the figure analyzing process and time for figure unfolding becomes longer than time for the figure analysis. This is because the cell data 112 is formed in a microprogramming manner and the figure analysis can be effected by several steps, but each step must be effected for each pixel or every preset number of pixels of the figure in the figure unfolding process. Particularly, when the number of pixels of the figure is large or the number of figures is large, time for the figure unfolding process becomes extremely long.
Therefore, the pattern generation speed of the figure pattern generating apparatus is generally dependent on the unfolding speed of the figure unfolding section 103.
For the reasons described above, in the conventional figure pattern generating apparatus, the operation speed higher than the figure unfolding speed of the figure unfolding section cannot be attained and the pattern generation speed is automatically limited.